From Choral Ode ("O Dirce, holy river") to the exit of the messenger (the herdsman of Mount Cithaeron) (Lines 520-774):
Initially addressing the holy river of Thebes, the Chorus cries out about the rejection Bacchus faces in the place of his birth. The Bacchae promise that soon Thebes will know his name, and they cry out against Pentheus' outrages. In language replete with striking nature imagery, they pray to Bacchus to deliver them. Suddenly, lightning and thunder strike overhead, and the earth shakes; the Chorus becomes insane with fear. Dionysus' voice shouts out from within the palace. The palace is completely destroyed. Flames blaze from the tomb Semele. The Chorus prostrate themselves.
Dionysus emerges from the rubble, and he talks casually to the Chorus. He is still pretending to be a mortal man. He escaped the manacles with ease; inside the cell, as Pentheus tried to manacle Dionysus, the young king was deceived by an illusion. A bull came to the cell, and Pentheus, made mad by the god, thought the bull was Dionysus. He tried to chain the bull, but the task was impossible. Later, when the palace was in flames, Dionysus made an illusory double of himself to mislead Pentheus, who stabbed with his sword into thin air. Dionysus hears Pentheus approaching, and he says that Pentheus does not even have the power to anger him: "Wise men know constraint: our passions are controlled" (l. 642).
Pentheus enters, furious, demanding to know how Dionysus escaped. Dionysus answers that the god delivered him. Pentheus trades more barbs with Dionysus, and a Messenger, a herdsman from Mount Cithaeron, enters. The Messenger has fantastic news about the Maenads and the miracles they do; Pentheus is abrupt and bullying with the man, and the fearful Messenger asks if he can share the news, in his own words, without fear of punishment. Pentheus promises that the Messenger will not be hurt, but he also promises that the more terrible the news is, the more terrible the punishment of the new cult's priest will be.
The Messenger and some fellow herdsmen stumbled on three companies of Maenads, one of which was led by Pentheus' own mother, Agave. The women were sleeping, chaste and composed (instead of drunken and lewd, as Pentheus has imagined). On hearing the lowing of the cattle, the women woke. Some of the women's fawn-skins had slipped: they used snakes to refasten them. The mothers who had left infants behind in the city were nursing wolf cubs and young gazelles. One of the women struck the ground with her thyrsus and a cool spring began to flow freely from the ground. Another woman did the same, making a spring of wine. Thirsty Maenads scratched at the earth, and milk came bubbling up freely; honey flowed from the thyrsi. Then the Maenads began to celebrate wildly, dancing and running with the wild beasts. The herdsmen, hoping to win the favor of the king, decided to ambush the women; the men barely escaped alive. Provoked, the women then turned against the cattle, ripping the animals apart with their bare hands. The villages in the foothills were next: the Maenads destroyed everything in sight. When the men of the villages tried to fight back, the Maenads routed them without effort. The Maenads then returned to the wilderness and their celebration, the snakes licking the blood from the women's skin. The Messenger tells Pentheus to welcome the god. Dionysus is powerful, and he has many gifts to offer; it is madness to oppose him.
Pentheus' humiliation begins. The description of his attempt to manacle Dionysus neatly captures the futility of his struggle: he is attempting to chain down a wild bull, a symbol for the force of nature. He does not know what he faces, and the effort leaves him exhausted; he has been made to look ridiculous. The god humiliates Pentheus again with the false image of himself; Pentheus takes wild swings at the air, and his physical strength comes to nothing. But the more miracles occur, the more Pentheus becomes obsessed with defeating the new religion.
Dionysus, just before Pentheus' entrance, makes a claim to wisdom. He says that Pentheus means nothing to him, and that the wise know how to restrain their passions. But by his own standards, Dionysus will fail. His revenge against Pentheus and his house will be excessively brutal. Remember that Pentheus is very young: this is Euripides' deliberate choice, which destroys the god's claim of restraint or wisdom. Wisdom is not a common attribute of boys who are Pentheus' age, but the god refuses to show any mercy to Pentheus. He makes no allowance for the boy's youth, and the lack of restraint exposes Bacchus as brutal and vindictive, god or not.
Pentheus claims to be rational, but in reality he is absolutely irrational. The miracles continue, and by rejecting them as proof of Dionysus' divinity, Pentheus proves he is as irrational and deluded as the most feverish cultist. His treatment of the Messenger shows his lack of self-control; he is short-tempered, and his behavior toward his subjects is tyrannous. He promises that the more terrible the news is, the more he will punish the priest for teaching this new kind of magic to the women: with this resolution, he shows the extent of his blindness. Even before hearing the Messenger's words, Pentheus has already rejected anything offered as proof of Bacchus' divinity. He does not accept, as the Messenger does, that the events are miraculous. He has reached his conclusion before hearing the evidence. This behavior is not rational or intelligent; for Pentheus, this struggle is no longer (if it ever was) about the truth. It is about winning.
The Messenger's story depicts a world where the women have rejoined the primal forces of nature. Nature and wilderness are an important theme of the play, and here a face of nature is pitted against the markers of human civilization. Like the forces of nature, Bacchus is capable of both destructiveness and benevolence. Initially, we see the Maenads in a complex mutual relationship with nature. It is no accident that women are Bacchus' chosen vessels. Because of the process of childbirth, women are seen as being more intimately connected with nature's cycles of birth and death. Nature provides for the Maenads abundantly, springs of wine and milk miraculously welling up from the ground. The women also provide for nature: the mothers among them provide milk for young gazelles and wolf cubs. But by attacking the women, the herdsmen incite the other face of nature: brutal, destructive, overpowering. Note that the women attack those things connected to civilization: domestic animals, villages. The beasts that have been mastered by man are destroyed; the buildings, crafted by the skill and ingenuity of man, are pillaged. The forged weapons are useless against the Maenads, while the Maenads, armed only with branches plucked from the forests, inflict mortal wounds on the villagers.